1. Field of the Invention
The present invention relates to a shock absorber incorporated into the mechanism that supports the front wheel of a bicycle on the frame of the bicycle. In particular, the invention pertains to a damping and buffering shock absorber mechanism mounted between the stem of a bicycle handlebar and the front wheel fork of a bicycle.
2. Description of the Related Art
Shock absorber mechanisms for motorcycles are well-known. For instance, shock absorber mechanisms have been mounted to the portion of the front of the motorcycle frame which supports the front fork and a handlebar stem. Further, such shock absorber mechanisms have been provided as a part of the handlebar stem and fork stem.
On a motorcycle, the shock absorber mechanism typically requires two parallel units because of size, weight and complexity of motorcycle itself. However, bicycles are smaller and lighter, generally, than motorcycles and therefore the complexity and massiveness of motorcycle shock absorber systems are inappropriate. Mountain bikes, in particular experience the shocks due to uneven surfaces and benefit greatly from shock absorbers. However, the motorcycle shock absorber systems, being massive and complex are difficult to properly arrange on a mountain bike frame.
Conversely, the handlebar stem type shock absorber mountable between the handlebar stem and fork stem of the front of a mountain bike could absorb impacts using one shock absorber mechanism, if one would fit into the small dimensions of a bicycle frame. Such a mechanism would need to have the advantage of less parts and lighter weight. A well-known example of this type of shock absorber mechanism is the HeadShok.TM. manufactured by the American company Cannondale. In the HeadShok.TM., there is an oil/air pressure system and a urethane rubber system. The oil/air pressure system obtains a buffering effect using an air pressure cylinder and a dampening effect using an oil pressure cylinder. Further, the urethane rubber system obtains a buffering effect and a dampening effect using urethane rubber.
Because the conventional oil/air pressure system shock absorber mechanism uses an oil cylinder, if an oil leak occurs due to deterioration with age or damage to the packing, the packing must be replaced. This is something that makes maintenance difficult. Moreover, the urethane rubber characteristics of the urethane rubber system change due to deterioration with age. Further, only one material is used for both the buffering effect and dampening effect. Consequently, the dampening and buffering characteristics cannot be independently changed. Settings for the buffering effect and dampening effect, depending on the road surface and usage conditions, cannot be changed or fine tuned.